Shaders randomly take a big amount of time to compile

We are now working on a UE4 X1 game project which needs to cook a big amount of data.

We find there are quite a lot situations that the shader compiling takes a big amount of time. For example, in the following cooking log:

[2015.04.21-18.11.00:265][ 0]LogCookCommandlet:Display: Cooking /Game/Maps/IvyLair_B1_Static → D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/XboxOne/CityUE4/Content/Maps/IvyLair_B1_Static.umap
[2015.04.21-18.11.16:724][ 0]LogSavePackage:Display: Save=16457.992188ms
[2015.04.21-18.11.16:725][ 0]LogSavePackage:Display: Async saving from memory to ‘D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/XboxOne/CityUE4/Content/Maps/IvyLair_B1_Static.umap’
[2015.04.21-18.11.17:034][ 0]LogCookCommandlet:Display: Adding package to manifest /Game/Packages/OBJ/OBJ_TV/Screen/MAT/OBJ_TV_Screen_Noise_blue_Mat, D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/[Platform]/CityUE4/Content/Packages/OBJ/OBJ_TV/Screen/MAT/OBJ_TV_Screen_Noise_blue_Mat.uasset, /Game/Maps/Catwoman/IvyLair_B1_Static
[2015.04.21-18.11.17:035][ 0]LogCookCommandlet:Display: Up to date: D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/XboxOne/CityUE4/Content/Packages/OBJ/OBJ_TV/Screen/MAT/OBJ_TV_Screen_Noise_blue_Mat.uasset
[2015.04.21-18.11.17:036][ 0]LogCookCommandlet:Display: Adding package to manifest /Game/Packages/VEG/VEG_Plants/Gardens/MAT/VEG_Plants_Gardens_WallVeg02, D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/[Platform]/CityUE4/Content/Packages/VEG/VEG_Plants/Gardens/MAT/VEG_Plants_Gardens_WallVeg02.uasset, /Game/Maps/IvyLair_B1_Static
[2015.04.21-18.11.17:037][ 0]LogCookCommandlet:Display: Cooking /Game/Packages/VEG/VEG_Plants/Gardens/MAT/VEG_Plants_Gardens_WallVeg02 → D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/XboxOne/CityUE4/Content/Packages/VEG/VEG_Plants/Gardens/MAT/VEG_Plants_Gardens_WallVeg02.uasset
[2015.04.22-03.44.13:870][ 0]LogSavePackage:Display: Save=90978.843750ms
[2015.04.22-03.44.13:870][ 0]LogSavePackage:Display: Async saving from memory to ‘D:/Jenkins/AC-X1/UE4/CityUE4/Saved/Cooked/XboxOne/CityUE4/Content/Packages/VEG/VEG_Plants/Gardens/MAT/VEG_Plants_Gardens_WallVeg02.uasset’

The material asset VEG_Plants_Gardens_WallVeg02.uasset takes 9 hours to finish compiling and saving. We think it is the shader compiling takes this time.

Then engine is UE4.6 and the computer configuration is:

Processor Intel Core i7 4770K Quad Core LGA 1150 3.5GHz CPU Processor (or faster)
Memory 32 GB RAM
Video Card DX11 - NVidia GeForce 760 GTX

Do anyone meet the similar situation?

Actually on some other similar PC, this material spends far less time on compiling (can be 1-2mins).

We try to activate logging for the ShaderCompileWorkder. During cooking, we find some logs like:

[2015.04.23-08.44.06:305][ 0]LogCookCommandlet:Display: Adding package to manifest /Game/Packages/Characters_BM2/The_Riddler/Materials/MAT/Riddler_Hair_Blend_Anisotropy_1side_Reflct_Mat, E:/BM/BM-AC/UE4/CityUE4/Saved/Cooked/[Platform]/CityUE4/Content/Packages/Characters_BM2/The_Riddler/Materials/MAT/Riddler_Hair_Blend_Anisotropy_1side_Reflct_Mat.uasset,
[2015.04.23-08.44.06:309][ 0]LogCookCommandlet:Display: Cooking /Game/Packages/Characters_BM2/The_Riddler/Materials/MAT/Riddler_Hair_Blend_Anisotropy_1side_Reflct_Mat → E:/BM/BM-AC/UE4/CityUE4/Saved/Cooked/XboxOne/CityUE4/Content/Packages/Characters_BM2/The_Riddler/Materials/MAT/Riddler_Hair_Blend_Anisotropy_1side_Reflct_Mat.uasset
‘UE4Editor.exe’ (Win32): Loaded ‘C:\Program Files (x86)\Microsoft Durango XDK\xdk\FXC\amd64\SC_DLL.dll’. Cannot find or open the PDB file.
‘UE4Editor.exe’ (Win32): Loaded ‘C:\Program Files (x86)\Microsoft Durango XDK\xdk\FXC\amd64\D3DCompiler_46_xdk.dll’. Cannot find or open the PDB file.
‘UE4Editor.exe’ (Win32): Loaded ‘C:\Program Files (x86)\Microsoft Durango XDK\xdk\FXC\amd64\SC_DLL.dll’. Cannot find or open the PDB file.
‘UE4Editor.exe’ (Win32): Unloaded ‘C:\Program Files (x86)\Microsoft Durango XDK\xdk\FXC\amd64\SC_DLL.dll’
‘UE4Editor.exe’ (Win32): Loaded ‘C:\Program Files (x86)\Microsoft Durango XDK\xdk\FXC\amd64\D3DCompiler_46_xdk.dll’. Cannot find or open the PDB file.
‘UE4Editor.exe’ (Win32): Unloaded ‘C:\Program Files (x86)\Microsoft Durango XDK\xdk\FXC\amd64\D3DCompiler_46_xdk.dll’
[2015.04.23-08.49.05:999][ 0]LogShaderCompilers:Error: ShaderCompileWorker terminated unexpectedly! Falling back to directly compiling which will be very slow. Thread 1.
[2015.04.23-08.49.05:999][ 0]LogSavePackage:Display: Save=299702.312500ms

Do anyone know which cases will cause ShaderCompileWorker to terminate?

Any suggestions will help.

Best Regards,
Andy